dumb question, streaming music to a preamp?

Hi. I am trying to put together a low cost system for my daughter, who is sharing an appartment with a few friends. We have a Luxman L-480 integrated amp and some TMM floorstanding speakers I built from a kit. She has WiFi in her appartement. She would like to use Spotify, which claims CD quality and allows you to select play lists or albums from more than 5 million albums. So how to get the music to the Luxman amp? Could buy a Sonos unit, but that is $399, which is about 1/2 the cost of everything else so far. Do not want to use a phone as have data streaming limits. Do not want to use a dedicated computer or iPad as too expensive as well. Any ideas out there. Could stream from her computer, but it just can not be tethered to the Luxman amp with a RCA cord. And if stream from her computer over WiFi, what device picks it up and converts to analog for the Luxman? Thank you for your help. This area is changing really quickly, and I have never even thought about it before.
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Bluesound Node 2, self contained with integral DAC and MQA.
 Control via phone or laptop. 24 bit CD quality @$499
After reading the whole post, the more as I know is about Spotify music. How to convert Spotify music to common format. Since all Spotify music are DRM protected, there is no right for us to play all these download music in any format on any devices. If you really want to enjoy all these music on any devices freely, you can use a Spotify Music Converter to remove DRM protection at first. Now there are so many powerful DRM removal software on the Internet that are helpful to us. You can catch one to help you crack DRM protection and convert music to MP3, AAC, WAV, FAC, M4A, M4B, etc at faster speed with lossless quality. Wish this point is helpful to you.

Bluesound just came out with the Node 2i.  It's $499, but you may be able to pick up the previous Node 2 for quite a bit less now.  I just ordered one for $200 from my local dealer who took some in on trade.  I should have it in a few days and plan to put it in my main system.  It will stream Tidal, Spotify, Napster, Deezer, Qobuz, and a lot more.  It has an internal DAC and analog outs.  I'm planning to use my Auralic Vega for the DAC, but for what you've described the Node 2 sounds like a good option.
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